Unlike typical transit data in which dips in the light curve occur to a constant proportion and at regular intervals, the star KIC 8462852 certainly posed a peculiarity. There must be something in the way…
Without thinking too hard, there’s a high possibility that there is some sort of interstellar material orbiting quite close to the star. This doesn’t seem like a shocking explanation, as interstellar dust and gas are very abundant across the universe, and are responsible for the formation of planetary systems. What may tip the scales in favour of one hypothesis and not another are the more specific details – for instance, is there enough material to account for the dips in the light curve?
There have been suggestions that KIC 8462852 is a relatively young star and has a ring of coalescing material around it, just like our Sun would have had during the formation of the Solar System. However, data has been collected which suggests the star is not this young, and analysis has indicated that there is likely no coalescing material within a few AU of the star (a few AU is approximately the distance from the Sun to Jupiter).
Could the star not just be mature but also have debris floating around? Perhaps, though a lot of debris is required to account for the depth of the dips and this is only a possibility if a collision between two large rocky bodies has has recently occured. Debris will tend to coalesce due to gravitational forces, or float away if they are too spread out. A collision of this size would emit detectable infrared radiation, which has not been observed, which therefore also labels this hypothesis as an unlikely one.
Another suggestion involves comets – a cloud of disintegrating comets as they approach the star can obscure a proportion of the star’s light. A small star has been found within close proximity to KIC 8462852, and there’s a possibility that this star can cause comets to fall into the orbit of KIC 8462852; however astronomers think it’s unlikely that there could exist a high enough number of comets to block out a major proportion of the star’s light as indicated by the light curve.
And of course, when you run out of hypotheses, it’s always fun to blame the aliens. A civilisation like ours can harness all the energy we need from the Earth alone, but if our population were to grow and our demand for energy were to rise, the Earth alone would not be sufficient. A star is a source of tremendous amounts of energy – think about how warm and bright the Earth becomes during the day due to us facing the Sun, and we’re only absorbing a microscopic proportion of the Sun’s energy.
Aliens would need to build a megastructure which could envelop a star and harness a major proportion if not all of its energy, and this megastructure has been coined a ‘Dyson sphere’. Dyson spheres have made appearances in various science fiction novels since the mid- twentieth century. Indeed, dyson spheres can account for irregular dimming in the light curve, but the lack of evidence for extraterrestrial life also gives this hypothesis a low probability of being true.
Annoyingly, not one of the current explanations are considered far more likely than the others… but it’s intriguing (and perhaps disturbing) to think that, if aliens on KIC 8462852 have ever observed us, then they would seeing what the Earth was like 1,300 years ago (and likewise we’re observing them 1,300 years into their past).